Easy On, Easy Off

Efficiency of the hydrogel sealant (dyed in green) in sealing a puncture on a vein surface, preventing leakage (a). Sealant washed off upon exposure to an amino acid solution for wound re-exposure and further treatment (b&c).

Adherence of the hydrogel sealant to human skin tissue (a) and exposure to an amino acid solution for triggered dissolution (b).

Researchers at Professor Mark Grinstaff’s (BME, Chemistry, MSE) lab and Boston’s Beth Israel Deaconess Medical Center (BIDMC) have developed a highly absorbent hydrogel that not only seals wounds, but can later be dissolved and gently removed. Intended for wounds that must be quickly closed to stem blood loss and prevent infection, but later reopened for more extensive treatment, the biocompatible gel is particularly suitable for injuries sustained in combat or remote areas, and may well end up in the toolkits of first responders and emergency room medical personnel.

Grinstaff and his collaborators reported their first findings in Angewandte Chemie, Europe’s leading chemistry journal.

Reopening a wound can cause damage to injured tissue, particularly when blood-clotting agents or dressings were initially applied. The BU-BIDMC team’s wound closure system is the first that not only stops bleeding for several hours, adheres to the wound site and is easy to apply, but also is easy to remove in a controlled manner before surgery or other procedures.

“Today’s trauma wound closure materials, once applied, must later be cut out,” said Grinstaff. “We’ve introduced a mild process for removing a hydrogel sealant from a wound where there’s no cutting or scraping involved.”

The sealant is administered via double-barreled syringe, with each barrel containing a different compound. Once the two compounds are pushed out of the syringe onto a surface, they combine within seconds to form a honeycomb-like network of cross-linked chemical bonds. The resulting hydrogel absorbs fluid on the surface, has the consistency of gelatin and sticks like an adhesive, remaining intact for several days. Adding a solution of cysteine methyl ester, a derivative of a natural amino acid, to the hydrogel causes the gel’s cross-linked bonds to break apart and the gel to dissolve within 30 minutes.

The idea for a wound-sealing reversible hydrogel emerged about 18 months ago when Grinstaff, who has long nurtured an interest in developing hydrogels and other materials that possess reversible properties, met with BIDMC/Harvard Medical School Assistant Professors of Orthopaedic SurgeryEdward K. Rodriguez and Ara Nazarian (also an adjunct assistant professor of biomedical engineering at BU) to explore how they treat wounds and what could be improved.

Since then Grinstaff, postdoctoral fellow Cynthia Ghobril, BME graduate student Kristie Charoen, and the two BIDMC colleagues, with support from the National Institutes of Health, designed and developed the hydrogel, and performed tests on living and extracted tissue to ensure that the material is safe, non-toxic and sufficiently strong. Over the next six months, with funding from the Wallace H. Coulter Foundation, the team plans to evaluate the hydrogel for the treatment of burns.